Locking device for electric-light bulbs



J. P. CASSIDY.

LOCKI'NG DEVICE FOR ELECTRIC LIGHT BULBS.

APPLICATION FILED APR. 7 1919.

1,860,266, 6 Patented Nov. 30, 1920.

INVENTOR yam aw UNITED STATES PATENT OFFICE.

JAMES P. CASSIDY, OF NEW HAVEN, CONNECTICUT, ASSIGNOR TO JOHN W. LADID, OF NEW HAVEN, CONNECTICUT.

LOCKING DEVICE FOR ELECTRIC-LIGHT BULBS.

Specification of Letters Patent. Patented NOV. 30, 1920.

Application filed April 7, 1919. Serial No. 288,029.

To all whom it may concern Be it known that 1, JAMES P. CAssInY, citizen of the United States, residing at New Haven, in the county of New Haven and State of Connecticut, have invented certain new and useful Improvements in Looking Devices for Electric-Light Bulbs; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains, to make and use the same. v

' My invention relates to a locking device to prevent surreptitious removal of electric light bulbs from their sockets, and it consists in certain details of construction to be more fully set forth in the following specification.

Referring to the accompanying drawings wherein certain figures and letters of reference indicate. like parts throughout the several views:

Figure'l represents a detail view of the locking device; 7

Fig. 2 is a broken view of lamp casing partly in section showing the lock mounted on the threaded socket shell in the porcelain base, or socket;

F ig. 3 is an enlarged broken view partly in section of the lamp casing, and the glass bulb showing the latter seated around the threaded, shell of the base or socket with the lock in operative position;

Fig. 4 is an enlarged broken view partly in section of the lower device, and 1 V Fig. 5 is a broken View of an ordinary glass bulb with its threaded shell.

The locking device consists of the coil 1 carrying at its lower end the metal strip 2 to serve as an anchor or locking means in connection with the shell or casing 3, as follows: After the casing is in place, the.coils of the lock are engaged with the metal threaded shell 4, Fig. v2, until the edge of;

anchor 2 rests on the shoulder 6 of the socket 7 It will be understood that the anchor Wedges between the shoulder 6 and the lower thread of the shell 4. Also it is frictionally engaged by the said shell 4 and.

casing 3. After the coils are in lace on the shell 4, the said shell is slipped into thecasing 3 from the bottom or larger end, and

thus the anchor is securely locked and part of the locking j wedged in place, sothat it will be impossible to move the same without dismantling the complete socket. This will leave several coils of the lock projecting above the threaded socket shell of the socket as shown. The lamp shell 8 is then screwed into the threaded socket shell of the socket in the usual A manner.

In bringing the shell 8 into engagement with the socket, the exposed or projecting coils of the lock will be compressed, and as the shell is being screwed into' the socket these exposed coils will also engage the 3 the free end of the anchor 2 is forced inward by the frictional contact of the casing therewith, and when the anchor rests on the shoulder 6 of the socket, this wed ing and friction as before described is su cient to prevent further travel of the lower end of the spiral coil of the look while the lamp shell is being screwed into the socket in'the direction of arrow 12, Fig. 3. This inward movement will tend to expand or open the exposed coils a, and when the electric bulb .10 is seated, the reactionary grip of the coils a against the shell 8 will effectually prevent a reverse movement of the bulb. The only way to release the gripof these upper coils is by simply lifting the free end 11 and thus break the grip of the coils when the bulb can be readily unscrewed. As this free end is entirely hidden within the embrace of the casing 3, it can only be reached by breakingthe bulb, which bulb will then have no commercial value. When'the lamp is burned out, the bulb will then be broken and its mentioned. v

The length of the anchor 2 is immaterial so long as it serves the purpose for which it is intended.

is secured by one end to the end of the lower a shell easily removed in the manner before It will be understood that all parts of the electric lamp shown are old and form no partof my invention, which consistsonly in the a plication of my improved lock thereto and or the purpose above set forth Having thus described my invention, what I claim is 1.- In combination with an. electric lamp socket comprising an insulating base, and a threadedcontact shell fitting snugly with an outer casing, a lock comprising a metal coil and a locking piece secured to the lower end of the coil, said coil engaging the outer surface of the shell, and said locking piece projecting adjacent to the lower inner end of the shell so as to be securely locked and wedged between the base and the lower thread of the shell, said coil having a part which projects above the open end of the socket and which engages the threaded lamp base when the latter is inserted in the socket.

2. In combination with an electric lamp socket comprising an insulating base, and a threaded contact shell fitting snugly with an outer casing, a lock comprising a metal coil and a locking piece composed of a curved member secured at one end to the lower end of the coil and having its opposite end free, said coil engaging the outer surface of the shell, and said locking piece projecting adjacent to the lower inner end of the shell so as to be securely locked and wedged between the base and the lower thread of the shell, said coil having a part which projects above the open end of the socket and which engages the threaded lamp base when the latter is inserted in the socket.

In testimony whereof I afiix my si iiature.

JAMES P. CASbIDY. 

